Cyclic aminoborane compounds



United States Patent 10,708/62 16 Claims. .(Cl. 260-551) This invention relates to boron compounds and in particular to novel cyclic aminoboranes.

There are therefore provided, in accordance with this invention, the novel aminoboranes having the following wherein R is selected from the group consisting of alkyl of 1 to 8 carbon atoms, cycloalkyl in which the ring contains 7 carbon atoms, and aryl; R' is selected from the group consisting of hydrogen and alkyl of l to 5 carbon atoms; R" is. an alkyl of 1 to 5 carbon atoms; and n is an integer selected from 2 and 3.

Illustrative examples of groups'represented by R are the alkyl groups, straight or branched chain, such as methyl, ethyl, propyl, isopropyl, butyl, tert.-butyl, secpentyl, hexyl and octyl, as well as the cycloalkyl groups such as cyclopentyl, cyclohexyl and cycloheptyl. R can also represent an aryl group, especially the monocyclic aryl groups such as phenyl and nuclear substituted phenyl. Typical nuclear substituents are lower alkyl and alkoxy, such as methyl, ethyl and methoxy and the halo radicals, such as chloro and bromo.

Typical examples of alkyl groups which canbe represented by R and R" in the above formulae are methyl, ethyl, propyl, isopropyl, butyl, pentyl, sec-pentyl, and the like.

When n represents 2 in the above formulae, the compounds are derivatives of 1,3,2-diazaborolidine and when n represents 3, the compounds are derivatives of 1,3,2- diazaborinane. Representative examples of the compounds of the present invention include Z-dimethylamino-1,3-dimethyl-1,3,2-diazaborinane N,N-dimethyl-N,N-bis( 1,3-dirnethyl-1,3,2-diazaborinyl) trimethylenediamine 2-dimethylamino 1,3-diisopropyl-1,3,2-diazaborolidine N,N'-diisopropyl-N,N'-bis( l,3-diisopropyl-l ,3,2-diazaborolo ethylenediamine s Z-dimethylamino-l,3-di-tert.-butyl-1,3,2-diazaborolidine Z-di-n-butylamino-l,3-diethyl-1,3,2-diazaborinane Z-diethylamino-1,3-dicyclohexyl-l,3,2-diazaborolidine 2 di-n-hexyla-mino-1,3-diphenyl-1,3, 2-diazaborolidine The new compounds can be prepared by transamination reaction between a tris(rnonoalkylamino)borane or a tris(dialkylamino)borane and an N,N'-disubstituted ethyleneor trimethylene-diamineL Generally speaking,

compound of structure III as an. intermediate.

3,23%,465 Patented Aug. 17, 1965 such a transamination will occur most readily and completely when the diamine is less volatile than the amine corresponding to the tris(alkylamino)borane, and this represents a preferred aspect of the invention. According to the conditions employed, the reaction will give as the main product a compound of structure I or II, as represented by the following equations:

(1) in which R, R, R and ri have the significance previously assigned. 7

It is believed that compounds of structures II are then as represented by the following equations:

equimolar proportions of the reactants, or less advan- 'tageously, an excess of the tris(alkylamino)borane, are

used, the main product will be of type I; on the other hand, if the diamine is in excess, preferably in a molar ratio to the tris(alkylamino)borane of about 3:2, formation of a compound of structure II is favored, with a As for reaction periods, it appears that reaction (a) is relatively fast, while reactions (b) and (c) are very considerably slower. If, therefore, the process is interrupted, e.g., by cooling the reactants,'. at an early stage, the production of a compound of type I is favored.

The nature of the reactants will also influence the course of the reactions; Thus, if the size of the N-substituent of the diarnine (represented above by R) is bulky,

type I.

e.g., is a secondary or tertiary :alkyl group or a cyclic group, reactions (b) and (c) are much hindered and the erate all three stages oft-he reaction, and in so doing quires: B, 7.0; N, 27.1%.

' period.

favor the production of a compound of type 11, even under conditions which in the absence of a catalyst would give a compound of type I as substantially the sole or main product. As a catalyst there can be used an amine salt of a strong -acid such as the mineral acids, which can be added as such or formed in situ by adding an anhydrous strong acid. Examples of suitable acids are hydrogen chloride and sulfuric acid, especially the for mer. The amount of amine salt, whether added as such or formed in situ, is preferably about 0.1 to 5% of the weight of the whole reaction mixture. The reaction should be eifected in the absence of Water and oxygen. Thus, the reactants and any catalyst usedshould be anhydrous, and the reaction take place in an atmosphere of a dry inert gas, e.g., dry nitrogen or dry argon or other of the so-called Noble gases.

To carry out the reaction, the reactants and catalyst, if one is used, are heated to a temperature of 100-- 210 C., and preferably 140-200 C. to stop the reaction at any point, for example in order to produce a compound of type I as the sole or main product, this may be done by causing or allowing the temperature to drop below 100 C., such as to 5080 C. or lower. ing the amount of by-product amine formed; thus, it the product is to be a compound of type I, the reaction can be stopped, as by cooling the reactants as al- If it is desired i The process can be followed by observready described, when two molecular proportions of W amine have been liberated for each molecular proportion of t-ris(alkylamino)borane or diamine used as starting material.

The products, of whichever structure, can be separated from the reaction mixture by conventional means,

such as, for example, fractional distillation and crystallization.

The new compounds are useful as additives to leaded motor fuels, in that they tend to reduce the formation of combustion chamber deposits and reduce the effect of such deposits as are still formed. When incorporatedin lubricating oils they have valuable anti-corrosive properties.

The following examples are presented to illustrate the preparation of typical compounds of this invention, but it is to be understood that the invention is not to be limited to the specific examples given.

Example I A flask which was fitted with a reflux condenser and, in series therewith, a trap cooled to 78 C. was flushed out with dry nitrogen, and a mixture of tris(dimethylamino) borane (8.5 g.; 0.06 mole) and N,N-dimethyltrimethylenediamine (9.1 g.; 0.09 mole) was introduced. The mixture was heated to 160 C. for one hour, after which time 6.2 g. (0.14 mole) of dimethylamine had been evolved and collected in the cold trap. This corresponds to 78% of the theoretical dimethylamine available. Distillation of the residue yielded 2.77 g. of 2-dimethylamino 1,3 dimethyl 1,-3,2 diazaborinane, B.P. 36 C./0.1 mm.

Analysis.-Found: B,

6.5; N, 27.1. C H BN re- 7 Example 2 A mixture of N,N'-dimethyltrimethylenediamine (28.1

g.; 0.28 mole) and tris(dimethylamino)borane (25.4 g.;

0.18 mole) was heated in a similar apparatus for three hours at 170 C. followed by one hour at 200 C. A total of 22.9 g. (0.51 mole; 96% of theory) of dimethylamine was collected in the cold trap during the heating Distillation of the residue yielded two fractions, one of B.P. 2933 C./0.7 mm., of which 4.75 .g. was obtained, believed to be 2-dimethyl-amino-1,3- dimethyl-1,3,2-diazaborinane, and a second (16.7 g., yield 56.7%) boiling at 136 C./0.03 mm., M.P. 39- 40.5 0., which was identified as N,N'-dimethyl-N,N-

, 4 bis(1,3 dimethyl 1,3,2 diazaborinyl) trimethylenediamine.

Analysis-Found: C, 54.3; H, 11.7; B, 6.8; N, 25.8%; M=335. C H B N requires: C, 55.9; H, 11.3; B, 6.7; N, 26.1%; M=322.

An intermediate fraction (6.1 g.) was collected at 82-87" C./ 0.05 mm., and assumed to be the corresponding compound of type III, N,N-dimethyl-N-(1,3-dimethyl-1,3,2-diaza'boriny1)-trimethylenediamine.

Example 3 A mixture of tris(dimethylamino)borane (9.17 g.; 0.064 mole) and N,N-diisopropylethylenediamine (14.11 g.; 0.10 mole) was heated for 12.5 hours at 170-175 C. and for a further 5.5 hours at 200 C. Dimethyl- -amine,(6.8 g.; 0.15 mole; 79% of theory) was collected in a cold trap. Distillation of the residue yielded 8.2 g. (0.042 mole; 70%) of Z-dimethylamino-l,3-diisopropyl-1,3,2-diazaborolidine, B.P. 91.5 C./ 10 mm.

Analysis-Found: B, 5.7; N, 21.0%; M=185. C H BN requires: B, 5.5; N, 21.3%; M:197.

Example 4 Example 5 A mixture of tris(dimethylamino)borane (11.0 g.;

0.08 mole), N,N'-di-t-butylethylenediamine (13.3 g.; 0.08 mole) and 0.5 g. of methylammonium chloride was heated for 5 hours at C. followed by 24 hours at C. During this time 6.7 g. (0.15 mole; 97% of theory) of dimethyl-amine was evolved. Distillation of .the residue yielded 13.1 g. (75.5%) of Z-tlimethylamino- 1,3-di-t-butyl-1,3,2-diazaborolidine, B.P. 9294 C./5

Analysis.--F-ound: B, 4.9; N, 18.2. quires: B, 4.8; N, 18.6%.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed.

We, therefore, particularly point out and distinctly claim as our invention:

1. The compounds represented by the formulae 0121 12 8 P13 Tephenyl; R is selected from the group consisting of hydrogen and alkyl of 1 to 5 carbon atoms; R" is alkyl of one and which comprises heating at a temperature of 100210 C; a mixture of a diamine of the formula RNH(CH ),,NHR and a tris(alkylamino)borane of the formula in the absence of water and free oxygen, separating byproduce amine as it is formed, and isolating aminoborane from the reaction mixture, wherein R is selected from the group consisting of alkyl of 1 to 8 carbon atoms, cycloalkyl of -7 carbon atoms, phenyl, lower alkylphenyl, lower alkoxyphenyl, and halophenyl; R is selected from the group consisting of hydrogen and alkyl of 1 to 5 carbon atoms; R is alkyl of 1 to 5 carbon atoms; and n is an integer selected from 2 and 3.

8. The process for producing an aminoborane of the formula which comprises heating at a temperature of 100210 C., substantially equimolar amounts of a tris(alkylamino)borane of the formula (R R N /3 B and a diamine of the formula RNH(CH N1-IR in the absence of water and free oxygen, separating by-product amine as it is formed until about two molecular proportions have been removed, and isolating said aminoborane from the reaction mixture, wherein R is selected from the group consisting of alkyl of 1 to 8 carbon atoms, cycloalkyl of 5-7 carbon atoms, phenyl, lower alkylphenyl, lower alkoxyphenyl, and halophenyl; R is selected from the group consisting of hydrogen and alkyl of 1 to 5 carbon atoms; R" is an alkyl of 1 to 5 carbon atoms; and n is an integer selected from 2 and 3.

9. The process for producing an aminoborane of the formula which comprises heating at a temperature of -210 C. a mixture of a diamine of the formula RNH-- CH NHR and a tris(alkylamino)borane of the formula (R R N A B in a diaminezborane molar ratio of about 3:2 and in the absence of water and free oxygen, separating by-product amine as it is formed, and isolating said aminoborane from the reaction mixture, wherein R is selected from the group consisting of alkyl of 1 to 8 carbon atoms, cycloalkyl of 5-7 carbon atoms, phenyl, lower alkylphenyl, lower alkoxyphenyl, and halophenyl; R is selected from the group consisting of hydrogen and alkyl of 1 to 5 carbon atoms; R" is an alkyl of 1 to 5 carbon atoms; and n is an integer selected from 2 and 3.

It). The process of claim '7 in which said mixture is heated at a temperature or" 200 C.

11. The process of claim 7 in which said mixture is heated in the presence of a catalytic amount of amine salt of a mineral acid.

12. The process of claim 9 in which said mixture is heated in the presence of a catalytic amount of amine salt of a mineral acid.

13. The process of claim 8 in which the reactants are heated at a temperature of 140200 C.

14. The process of claim 9.in which said mixture is heated at a temperature of 140200 C 15. A compound of the formula:

a (CH2) 5 B Alkyl Alkyl wherein Alkyl is a lower alkyl group. 16. A compound of the formula:

wherein Alkyl is a lower alkyl group. 

1. THE COMPOUNDS REPRESENTED BY THE FORMULAE
 7. THE PROCESS FOR PRODUCING AMINOBORANES OF THE FORMULAE 